Preparation of aryl magnesium chloride



e- CHLO war 0. ciiats'stdfiiartia R.

" Micli.,l as'si'gnprsf to' The panyilvlidland, wen,

{I'he 3present invention concerns an improved method .of preparing 1 arylgmagnesium chlorides having the general formula I '1' wherein It represents aromatic residue" of the V b nzenese i s Ary masnesium io d iand the, messa ing are relatively inexpensive and, from a cost viewscription is purely wherein point, would be well adapted for commercial use in theimanner describedabove. Aromatic chlorides,,however,aexhibittbut slight reactivity to-' ward magnesium under the conditions generally employed in preparing Grignard reagents, hence their employmentfor such purpose, even on laboratory scale, has been considered non-feasible up to the present time. 1

,We have now found that an aryl magnesium chloride of the benzene series may be prepared in good yield, at low cost, and in a brief period of time through heating a chloro-benzene compound with metallic magnesium under superatmospheric pressure, i. e. in a closed reactor, and at a temperature above about |3i3 C. and below the temperature at which appreciable decomposition occurs. The present invention, then, consists in an improved method of preparing an ary magnesium chloride having the general formula R. represents an aromatic residue of themethod being hereinafter benzene series, said fully described and particularlypointed out in the claims. v

The following description sets forth in detail but one of the various ways in which the principle of our invention may be practiced. It is to be understood, however, that the detailed deillustrative and is not'tobe' construed as a limitation on theinvention.

In preparing an aryl magnesium chloride of the class previously mentioned, we' heat a chlorobenzene compound with metallic magnesium under superatmospheric pressure and at a temperature preferably between aboutv 150 C.;and about 6; Claims. 5(01. es es) magnesium chloride product.

. 10 C-'; 1y completed through heati J g -in such manner 1 1 PQ iQdSO wQ IQ-I W $1 3. lo e hfi fi ay sometimes be required.z A catalyst, such as d n a ta yl od d a kr brqmi a k l ma nesiumhalide, copper, copper compound, ferric chloride 'etc.,' which jiseapameor promoti r r- G a d asmbr u ual' btb is the. heating operation.

e d sm e in" he o i sol s t fl ih as r h em r diidi ut, her ae e 'w l i sence of such catalyst.

ether, benzene, iso'amylet he with the arylchl oride prior to reacting the latter with magnesium, but we ha've found thatythe reaction will proceed F smoothly if inds'ol vent, other than the aryl chloride itselfi is employed.

The aryl magnesium chloride; for'med as Ja' product. inrour; process, is butsparinglyasolublein the aryl 1 chloride. itself, and: may be filtered gor th rwis r moved;therefromtin';s l d-form and ether, henmethenbenzesesolutes 2 my be. re is olve n; asu abl s lventu h as an isoamyl ether-benzene solution,,or in any other unreactive organic solvent capable-of dissolving the same and be employed'as a reactant 'in forming other aromatic compounds through the usual Grignard reactions." In practice, hcwever, we prefer to employ a aryl chloride over that quantity required to combine with the magnesium used to form an arylmagnesium chloride, and, after the latter is formed, to add to the reaction'mixturaa miX- l I slight excess of the V ture of ether and benzene in quantity'sufficient to dissolve anappreciable portion of'the aryl The, solution or mixture, so formed, may then beiemployed-di rectly as an agent in the usual Grignard reactions. During the preparation of phenyl magnesium chloride according to the generalrnethod described above, a relatively small quantity of diphenyl is sometimes formed, along, with the a 7 desired reaction product, phenyl magnesium chloride. p V I I I Other chlor -benzene .compoundsisuch asmonochloro, toluene, monochloro xylene; 2-' chloro-ethyl-benzene, I ortho-dichloro -benzene, monochloro-phenetole, monochloro-anisol, etc.', may be employed as reactants for the formation of the corresponding aryl magnesium chloride asherein described. In the case of ortho-dichlorobenzene, but one of the chlorine substituentsfapr V pears to be reactive toward magnesium;

Although, as previously pointed out, we may react a chloro-benzene compound with magne- 'maybe'obtained directly in solid form andjsubi v is as reactive-toward 40' r 1 We therefore particularly point out-and'dis- I sium under superatmospheri'c pressure and at any temperature above-about 130 C. and below that temperature at which:decomposition occurs, in practice we prefer to carry the reaction out at a temperature between, about' lfiq? and about 210 C. When'operatin'g at a" temperature substantially lower than1150 C.',-gthereaction tends to become sluggishl *When operating at a teln t perature substantially higher than 210 7 C., '"an appreciable'q'uantity of diphenyl maygbe formed. 7

As previously pointed out, we'pref er to employ an excess of the chloro-benzene compound when practicing our invention. We may-,' -;however, em 4 ploy the chloro-benzenef compound. and,.mag-

nesium in equimolecular quantities or wema y use excess magnesium. 'In such case the product 'sequently be dissolved in a suitable organic solvent, such as those previouslymentioned and;

be employedas a reactant for the formaticn of other," organic compounds by me ns a: the {well knownjGrignar'd reaction.)

i j Throughout th'specification' and intheclaims,

the expression chIOr -benaene compound? is employed as referring "to a compound selected from the class consisting of Lchloro-benzen'e' and substituted chloro-benzenes; egggmonb'chlomtoluene, mono-chloro xylene, f 2-chloroethy1- benzene, ,ortho-dichloro-benzene, 'mondchlorophenetole, monochlo'ro anisol, etd; which '1 com;

pound doesvnotcontainiagroup radical which m e um i a ch rine substituent npsarid. compound w 'Other modes ofiapplyingthe principle'of our invention may be employed instead of those ex.-

plained, change being made as regards the methodiherein' disclosed, providing 1 the means stated by any of the following clalms,-:or the equivalent of such stated-means be employed.

V tinctly' claim as our inVentionr- 150;and about 210? 1'. The method of making'an aryl magnesium chloride. of the benzene series which comprises reacting a chloro-benzene' compound with metal- 'lic magnesium under superatmospheric pressure and at a temperature above about 130" C.and below the temperature at which appreciable decomposition 'oforganic components of the reac- ,tion mixture occurs.

chloride'ofthe benzene series which comprises reacting a chloro-benzene compound with metallic magnesium in the presence of a catalyst, ca-

pableof promotingformation' of a Grignard reagent undersuperatmospheric pressure, and at a temperature betweenabout 150 and about 210 C. o p

' 3. The method of making phenyl magnesium chloride which comprises reacting monochlorobenzene'with metallic magnesium under super atmospheric pressure and ata temperature above about 130" 0'. and below the temperature at which material decomposition of ldrganid' 'components of the reaction mixture occurs; l

, 4. The method of rnaking-phenyl magnesium chloride which comprises reacting monochlorof2. The method of making an aryl magnesium" benzene withmetallic-mag-nesim in' the presence of a catalyst capable-of promotingformation of j s benzene with metallic magnesium in a closed' reactor to a reaction temperature between about 0 v I A V EDGAR C. BRITION.

HAROLD- R. SLAGH. 

